main()//唐子豪
{
    int a,i,b,n;
    printf("There are following friendly-numbers pair samller than 3000:\n");
    for(a=1;a<3000;a++){
        for(b=0;i=1;i<=a/2;i++)
            if(!(a%i))b+=i;
        for(n=0,i=1;i<b/2;i++)
            if(!(b%i))n+=i;
        if(n==a&&a<b)
            printf("%4d..%4d,",a,b);
    }
}